Optical recording medium and its recording apparatus and reproducing apparatus

ABSTRACT

An optical recording medium which is constructed in a manner such that a plurality of recording areas in which an information signal is recorded along vortical spiral tracks are arranged in a ring shape on a recording surface and a vortex direction of the spiral track of the outside recording area among the plurality of recording areas differs from that of the spiral track of the inside recording area. When the information signal is recorded to the recording medium, the first writing device executes the writing operation from the outer rim side toward the inner rim side of the spiral track of the outside recording area and the second writing device executes the writing operation from the inner rim side toward the outer rim side of the spiral track of the outside recording area. When the recorded information signal is reproduced, the first reading device executes the reading operation from the outer rim side toward the inner rim side of the spiral track of the outside recording area and the second reading device executes the reading operation from the inner rim side toward the outer rim side of the spiral track of the outside recording area.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an optical recording medium and its recordingapparatus and reproducing apparatus. More particularly, the inventionrelates to an optical recording medium which can record and reproduceinformation at a high density and a high transfer rate and also relatesto its recording apparatus and reproducing apparatus.

2. Description of the Related Background Art

FIGS. 1 and 2 Show optical recording media according to conventionalrecording systems.

FIG. 1 shows an optical disc of the spiral recording system. In arecording area A of an optical disc 100, an information signal isrecorded along a spiral track 103 from a signal track start point S to asignal track end point E.

FIG. 2 shows an optical disc of the double spiral recording system. Inthe recording area A of an optical disc 101, information signals arerecorded along spiral tracks 104 and 105 from a first signal track startpoint S₁ and a second signal track start point S₂ to a first signaltrack end point E₁ and a second signal track end point E₂, respectively.Two light beams are simultaneously used when the information signals arerecorded to the optical disc of the double spiral recording system orthe information signals are reproduced from the optical disc.

In the optical disc of the spiral recording system shown in FIG. 1 andthe optical disc of the double spiral recording system shown in FIG. 2,a CAV (Constant Angular Velocity) recording system is adopted. As alight spot approaches the outside in the radial direction of the disc,therefore, a unit recording mark length increases, so that even in caseof the information of the same length, the recording mark length needsto be increased on the outer rim side and a recording density cannot beimproved.

An optical disc 102 using a 2-zone spiral recording system as shown inFIG. 3, therefore, has been proposed in order to improve the recordingdensity. Each track of an inside recording area A_(I) and an outsiderecording area A₀ is concentrically arranged on the optical disc 102. Aninformation signal is recorded in the inside recording area A_(I) alonga spiral track 106 from an inside signal track start point S_(I) to aninside signal track end point E_(I). Similarly, an information signal isrecorded in the outside recording area A₀ along a spiral track 107 froman outside signal track start point S₀ to an outside signal track endpoint E₀. Even in the optical disc using the 2-zone spiral recordingsystem, two light beams are simultaneously used when the informationsignals are recorded and reproduced.

In the optical disc shown in FIG. 3, although a data transfer rate ofthe inside recording area A_(I) differs from a data transfer rate of theoutside recording area A₀, the sum of the data transfer rates of bothareas is always constant.

In the optical disc using the 2-zone spiral recording system, therecording density of the outside recording area A₀ can be raised to avalue larger than that of the inside recording area A_(I) (namely, thedata transfer rate can be, raised) and the recording density of thewhole optical disc 102 can be increased.

In the image processes of a high definition television such as a highvision television, however, an amount of information to be processed perunit time is fairly large. There is, consequently, a problem such thatthe recording density is further raised than that of the optical discshown in FIG. 3 and, at the same time, a high data transfer rate has tobe realized.

SUMMARY OF THE INVENTION

It is, therefore, an object of the invention to provide an opticalrecording medium in which a high data transfer rate can be obtained anda recording density of an information signal is high.

Another object of the invention is to provide a recording apparatuswhich can obtain such a high data transfer rate and can record aninformation signal to an optical recording medium having a highrecording density of the information signal.

Still another object of the invention is to provide a reproducingapparatus which can obtain such a high data transfer rate and canreproduce an information signal recorded on an optical recording mediumhaving a high recording density of the information signal.

According to the invention, there is provided an optical recordingmedium in which a plurality of recording areas are arranged in a ringshape on a recording surface and an information signal is recorded ineach recording area along spiral tracks, wherein a vortex direction ofthe spiral tracks in the outside recording area among the plurality ofrecording areas differs from that of the spiral track of the insiderecording area.

According to the invention, there is provided a recording apparatus forrecording an information signal onto an optical recording medium whichis constructed in a manner such that a plurality of recording areas inwhich the information signal is recorded along spiral tracks arearranged in a ring shape on a recording surface and a vortex directionof the spiral track of the outside recording area among the plurality ofrecording areas differs from that of the spiral track of the insiderecording area, wherein said recording apparatus comprises a firstwriting device which is movable arranged for the outside recording areaand writes the information signal to the outside recording area and asecond writing device which is movably arranged for the inside recordingarea and writes the information signal to the inside recording area, andin a recording mode, the first writing device executes the writingoperation from the outer rim side toward the inner rim side of thespiral track of the outside recording area and the second writing deviceexecutes the writing operation from the inner rim side toward the outerrim side of the spiral track of the outside recording area.

According to the invention, there is provided a reproducing apparatusfor reading and reproducing an information signal from an opticalrecording medium which is constructed in a manner such that a pluralityof recording areas in which the information signal has been recordedalong spiral tracks are arranged in a ring shape on a recording surfaceand a vortex direction of the outside recording area among the pluralityof recording areas differs from that of the spiral track of the insiderecording area, wherein the reproducing apparatus comprises a firstreading device which is movable arranged for the outside recording areaand reads the information signal from the outside recording area and asecond reading device which is movably arranged for the inside recordingarea and reads out the information signal from the inside recordingarea, and in a reproducing mode, the first reading device executes thereading operation from the outer rim side toward the inner rim side ofthe spiral track of the outside recording area and the second readingdevice executes the reading operation from the inner rim side to theouter rim side of the spiral track of the outside recording area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are diagrams showing recording methods of conventionaloptical discs;

FIG. 3 is a diagram showing a recording method of an optical discproposed instead of the prior art;

FIG. 4 is a diagram showing an optical disc according to an embodimentof the invention;

FIG. 5 is a diagram showing zones in the optical disc of FIG. 4;

FIG. 6 is a table showing the orders of the zones in the recording andreproducing modes of an information signal;

FIG. 7 is a diagram showing a data transfer rate of each zone;

FIG. 8 is a block diagram showing schematically a recording apparatus ofthe invention;

FIG. 9 is a block diagram showing schematically a reproducing apparatusof the invention;

FIG. 10 is a diagram showing a recording ratio of data to the inside andoutside zones;

FIG. 11 is a block diagram showing specifically the recording apparatusaccording to the invention;

FIG. 12 is a flowchart showing the operation of the recording apparatusof FIG. 11;

FIG. 13 is a block diagram showing specifically the reproducingapparatus according to the invention; and

FIG. 14 is a flowchart showing the operation of the reproducingapparatus of FIG. 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will now be described in detailhereinbelow with reference to the drawings.

FIG. 4 shows a disc-shaped optical recording medium according to thepresent invention.

In FIG. 4, an optical disc 1 includes the ring-shaped inside recordingarea A_(I) and the ring-shaped outside recording area A₀ on a recordingsurface. In the inside recording area A_(I), the inside signal trackstart point S_(I) is located on the inner rim side of the disc 1 and aninformation signal is recorded along a spiral track 2 from the insidesignal track start point S_(I) to the inside signal track end pointE_(I). In the outside recording area A₀, the outside signal track startpoint S₀ is located on the outer rim side of the disc 1 and aninformation signal is recorded along a spiral track 3 from the outsidesignal track start point S₀ to the outside signal track end point E₀.Namely, the vortex direction of the spiral track of the inside recordingarea A_(I) differs from that of the outside recording area A₀. When theinformation signal is recorded and reproduced, an inside light beam intwo light beams is used for the inside recording area A_(I) and anoutside light beam is used for the outside recording area A₀.

In the optical disc 1 of the invention, further, a plurality ofconcentric zones are set in each of the inside and outside recordingareas A_(I) and A₀. The number of zones of the inside recording areaA_(I) is equal to that of the outside recording area A₀.

FIG. 5 shows, for example, a case where twenty-two ring-shaped zones 1to 22 are set to the optical disc 1.

In the optical disc 1 shown in FIG. 5, a recording density of theinformation signal increases as the zone position moves from the zone 1to the zone 22. A region of the zones 1 to 11 corresponds to the insiderecording area A_(I) of the disc 1 shown in FIG. 4 and a region of thezones 12 to 22 corresponds to the outside recording area A₀,respectively. Namely, the information signal is recorded from the zone 1toward the zone 11 in the inside recording area A_(I). The informationsignal is recorded from the zone 22 to the zone 12 in the outsiderecording area A₀.

The spiral track 2 in FIG. 4 is continuous in the inside recording areaA_(I). The spiral track 3 is similarly continuous in the outsiderecording area A₀.

The information signal is recorded in a manner such that the recordingdensity differs every zone in each spiral track.

In the optical disc 1 as shown in FIG. 5, the information signals arerecorded and reproduced in accordance with the orders shown in FIG. 6.

In FIG. 6, the recording density of the information signal increases asthe zone position moves from the zone 1 toward the zone 11 in case ofthe inside recording area A_(I). The recording density decreases as thezone position moves from the zone 22 toward the zone 12 in case of theoutside recording area A₀. The recording density of the zone 11 issmaller than that of the zone 12. Since the recording density of theinformation signal is concerned With a data transfer rate, it will befurther described with reference to FIG. 7 showing data transfer rates.

In FIG. 7, the data transfer rates are shown as an example correspondingto the zones 1 to 11 of the inside recording area A_(I) and the zones 12to 22 of the outside recording area A₀. The recording and reproductionof the information signal are executed in accordance with the steporders in FIG. 6.

In each step, therefore, the sum of the data transfer rate of the zonewhich is processed by the inside light beam and the data transfer rateof the zone which is processed by the outside light beam is set to aconstant value 9.07 [Mbps]. When explaining with respect to step 1, forexample, the data transfer rate of the zone 1 is equal to 2.78 [Mbps]and the data transfer rate of the zone 22 is equal to 6.29 [Mbps]. Thetotal data transfer rate of them, therefore, is equal to(2.78+6.29=)9.07 [Mbps]. A similar result is also derived with respectto other steps 2 to 11.

FIG. 7 shows an example of calculations in case of a size of CD (compactdisc). The area is divided into 22 zones and the shortest pit length atthe innermost rim in each zone is equal to 0.71 μm. A (1, 7) modulationis used as a modulating system. A rotational speed of the disc is set to900 r.p.m.

A recording apparatus and a reproducing apparatus for the optical discas mentioned above will now be described.

FIG. 8 schematically shows the recording apparatus. An optical disc 200is rotated around an axis 204 by a spindle motor 202. Two opticalpickups 206 and 208 are individually movably arranged in the disc radialdirection above the optical disc 200. When recording, the inside opticalpickup 206 moves to the outside in the disc radial direction and theoutside optical pickup 208 moves to the inside in the disc radialdirection. Information signals are, consequently, recorded along thespiral tracks shown in FIG. 4.

Data 210 for recording as an information signal to be recorded issupplied to a data divider 214 through an error correction and encoder212. One of the divided data is supplied to the inside optical pickup206 through a recording encoder 216. The other one of the divided datais supplied to the outside optical pickup 208 through a recordingencoder 218. Explanation will now be made hereinbelow with respect tothe division of the recording data by the data divider 214 withreference to FIG. 10.

In FIG. 10, data 220 comprises recording data 222 and data 224 for errorcorrection. The data of a ratio (m) in the data 220 is recorded into theinside zone of the optical disc 200. The data of a ratio (n) is recordedinto the outside zone of the optical disc 200. An alternate long andshort dash line shown by reference numeral 226 denotes a data dividingline to divide the data 220 at a ratio of (m: n). The ratio (m:n)differs in dependence on the step in FIG. 6 and this point will now bedescribed with reference to FIG. 7.

As shown in FIG. 7, as the zone of the inside recording area moves fromthe zone 1 to the zone 11, the data transfer rate rises, so that theratio (m) increases. On the other hand, since the data transfer ratedecreases as the zone of the outside recording area moves from the zone22 to the zone 12, the ratio (n) is reduced. In every combination of theinside zone and outside zone, the sum of the ratios (m) and (n) is setto a predetermined value. This point corresponds to that the sum of thedata transfer rates is set to a predetermined value 9.07 [Mbps] in anycombination of the inside zone and outside zone.

FIG. 9 shows the reproducing apparatus and an optical disc 300 isrotated around an axis 304 by a spindle motor 302. The two opticalpickups 206 and 208 are individually movably arranged in the disc radialdirection above the optical disc 300. When reproducing, the insideoptical pickup 206 moves to the outside in the disc radial direction.The outside optical pickup 208 moves to the inside in the disc radialdirection. The information signal, therefore, is reproduced along thespiral tracks shown in FIG. 4.

The signals read out respectively from the disc 300 by the pickups 206and 208 are supplied to a data mixer 318 through amplifiers 310 and 312and decoders 314 and 316, respectively. The data mixer 318 mixes thedata from the zone of the inside recording area and the data from thezone of the outside recording area, so that the original data 220 inFIG. 10 is derived. A signal from the data mixer 318 is given asreproduced data 322 through an error corrector 320.

FIG. 11 specifically shows a constitution of the recording apparatus. InFIG. 11, data D from a signal processing section 10 is supplied to aninside FIFO memory 12_(I) and an outside FIFO memory 12₀ through anerror correction encoding memory 11. The data from both FIFO memories12_(I) and 12₀ is supplied to an inside optical pickup 16_(I) and anoutside optical pickup 16₀ through an inside recording encoding section13_(I) and an outside recording encoding section 13₀ and amplifiers14_(I) and 14₀, respectively. Both of the optical pickups 16_(I) and 16₀record the information signals onto the optical disc 1. The optical disc1 is rotated around an axis C by a spindle motor M. When recording, theinside optical pickup 16_(I) moves to the outside in the disc radialdirection. The outside optical pickup 16₀ moves to the inside in thedisc radial direction. The information signals, therefore, are recordedalong the spiral tracks 2 and 3 shown in FIG. 4.

An inside clock read signal C_(PI) and an outside clock read signalC_(P0) which were read out from the disc 1 by the pickups 16_(I) and 16₀are supplied to an inside clock extracting section 15_(I) and an outsideclock extracting section 15₀, respectively. A clock signal C_(I) for theinside zones extracted by the inside clock extracting section 15_(I) isused for synchronization in the inside FIFO memory 12_(I) and insiderecording encoding section 13_(I). Similarly, a clock signal C₀ for theoutside zones extracted by the outside clock extracting section 15₀ isused for synchronization in the outside FIFO memory 12₀ and outsiderecording encoding section 13₀.

A switch 22 is connected to the FIFO memories 12_(I) and 12₀. The switch22 switches a clock signal C_(W) for writing from a master clockgenerating section 20 to the IN side or OUT side. The IN side and OUTside of the switch 22 are connected to the inside FIFO memory 12_(I) andoutside FIFO memory 12₀, respectively. When the writing clock signalC_(W) is supplied to the inside FIFO memory 12_(I) from the IN side ofthe switch 22, the data D generated from the error correction encodingmemory 11 is written into the inside FIFO memory 12_(I). When thewriting clock signal C_(W) is supplied to the outside FIFO memory 12₀from the OUT side of the switch 22, the data D generated from the errorcorrection encoding memory 11 is written into the outside FIFO memory12₀.

A master clock which is generated from the master clock generatingsection 20 is supplied to a counter 21. A control signal from a CPU 23is further supplied to the counter 21. The counter 21 counts the numberof master clocks and supplies a count value A to a comparing section 19.The CPU 23 controls each section of the recording apparatus.

The read signals obtained by the pickups 16_(I) and 16₀ are supplied toa zone discriminating section 17. A zone number Z_(N) from each readzone of the disc 1 is discriminated by the zone discriminating section17. A zone combination number Z_(C) which is generated as adiscrimination result from the zone discriminating section 17 issupplied to a switching data ROM 18. The zone combination No. Z_(C)indicates one zone of the inside recording area A_(I) and one zone ofthe outside recording area A₀. A combination of those two zonescorresponds to each step in FIG. 6. Namely, each zone in the opticaldisc 1 constructs a zone combination every step in FIG. 6.

The switching data ROM 18 supplies data dividing line data X (refer toreference numeral 226 in FIG. 10) corresponding to the zone combinationNo. Z_(C) to the comparing section 19.

The comparing section 19 compares the data dividing line data X from theswitching data ROM 18 and the count value A from the counter 21 andcontrols the switching operation of the switch 22. Namely, when thecount value A is equal to or larger than the data dividing line data X(in FIG. 10, region on the right side than the dividing line 226), theswitch 22 is switched to the OUT side, thereby allowing the data of theerror correction encoding memory 11 to be written into the outside FIFOmemory 12₀. When the count value A is smaller than the data dividingline data X (in FIG. 10, region on the left side than the dividing line226), the switch 22 is switched to the IN side, thereby allowing thedata of the error correction encoding memory 11 to be written into theinside FIFO memory 12_(I).

The operation upon recording will now be described hereinbelow withreference to an operation flowchart of the recording system apparatus ofFIG. 12. The operation is accomplished by a control operation by the CPU23.

In step S1, the pickups 16_(I) and 16₀ read the signals including thezone No. Z_(N) from the optical disc 1. In step S2, the zonediscriminating section 17 discriminates the zone, thereby checkingwhether the combination is correct or not. If NO, the optical pickup16_(I) or 16₀ is moved to the next zone in step S3 so as to obtain thecorrect zone combination.

If YES in step S2, the data dividing line data X is read out from theswitching data ROM 18 in step S4. In step S5, the error correctionencoding (refer to error correction encoding memory 11) for the data Dto be recorded is executed. In step S6, the data dividing line data X iscompared with the count value A from the counter 21.

When X<A in step S6 (region on the left side than the dividing line 226in FIG. 10), the writing clock signal C_(W) is supplied from the masterclock generating section 20 to the inside FIFO 12_(I) through the switch22 in step S7. The data D to be recorded is written into the inside FIFO12_(I) in step S8. After that, a process in step S9 is executed. WhenX≧A in step S6 (region on the right side from the dividing line 226 inFIG. 10), on the contrary, the writing clock signal C_(W) is suppliedfrom the master clock generating section 20 to the outside FIFO 12₀through the switch 22 in step S10. The data D to be recorded is writteninto the outside FIFO 12₀ in step S11. After that, the process in stepS9 is executed.

In step S9, the clock signal C_(I) for the inside zones and the clocksignal C₀ for the outside zones are extracted from the read signals ofthe pickups 16_(I) and 16₀. In step S12, the data D is read out from theinside FIFO 12_(I) on the basis of the clock signal C_(I) for the insidezones and the data D is read out from the outside FIFO 12₀ on the basisof the clock signal C₀ for the outside zones. In step S13, the data Dread out on the basis of the clock signal C_(I) for the inside zones isrecording-encoded by the inside recording encoding section 13_(I) andthe data D read out on the basis of the clock signal C₀ for the outsidezones is recording-encoded by the outside recording encoding section13₀. In step S14, the recording to the relevant zone in the insiderecording area A_(I) of the optical disc 1 is executed by the opticalpickup 16_(I) and the recording to the relevant zone in the outsiderecording area A₀ of the optical disc 1 is performed by the opticalpickup 16₀. After completion of the execution of step S14, step S₁ isagain executed and the above operations are repeated.

In FIGS. 11 and 12, the data D from the error correction encoding memory11 is supplied to either one of the inside FIFO 12_(I) and the outsideFIFO 12₀ by the switching operation of the switch 22. Since both of theFIFOs 12_(I) and 12₀, however, always generate the data synchronouslywith the clock signals C_(I) and C₀, the data is simultaneously recordedin the inside and outside recording areas A_(I) and A₀ of the disc 1.

FIG. 13 specifically shows a construction of the reproducing apparatus.

In FIG. 13, the optical disc 1 is rotated around the axis C by thespindle motor M. When reproducing, the inside optical pickup 16_(I)moves to the outside in the disc radial direction. The outside opticalpickup 16₀ is moved to the inside in the disc radial direction. Theinformation signals, consequently, are reproduced along the spiraltracks 2 and 3 shown in FIG. 4.

The signals read out from the optical pickups 16_(I) and 16₀ aresupplied to the amplifiers 14_(I) and 14₀. The data D from theamplifiers 14_(I) and 14₀ is supplied to the inside FIFO memory 12_(I)and outside FIFO memory 12₀ through an inside decoding section 31_(I)and an outside decoding section 31₀, respectively. The data from both ofthe FIFO memories 12_(I) and 12₀ is mixed. The mixed data is supplied toa memory 30 for error correction and is supplied to the signalprocessing section 10.

The inside clock read signal C_(PI) and outside clock read signal C_(P0)in the read signals from the disc 1 are supplied to the inside clockextracting section 15_(I) and outside clock extracting section 15₀,respectively. The clock signal C_(I) for the inside zones extracted bythe inside clock extracting section 15_(I) is used for synchronizationin the inside FIFO memory 12_(I) and inside decoding section 31_(I).Similarly, the clock signal C₀ for the outside zones extracted by theoutside clock extracting section 15₀ is used for synchronization in theoutside FIFO memory 12₀ and outside decoding section 31₀.

The switch 22 switches the clock signal C_(R) for reading from themaster clock generating section 20 to the IN side or OUT side. The INside and OUT side of the switch 22 are connected to the inside FIFOmemory 12_(I) and outside FIFO memory 12₀, respectively. When thereading clock signal C_(R) is supplied from the IN side of the switch 22to the inside FIFO memory 12_(I) by the switching operation of theswitch 22, the data from the inside FIFO memory 12_(I) is read out andwritten into the memory 30 for error correction. When the reading clocksignal C_(R) is supplied from the OUT side of the switch 22 to theoutside FIFO memory 12₀, the data from the outside FIFO 12₀ is read outand written into the error correction memory 30.

The master clock which is generated from the master clock generatingsection 20 is supplied to the counter 21. The control signal from theCPU 23 is further supplied to the counter 21. The counter 21 counts thenumber of master clocks and supplies the count value A to the comparingsection 19. The CPU 23 controls each section of the reproducingapparatus although a control line is not shown.

The read signals by the pickups 16_(I) and 16₀ are supplied to the zonediscriminating section 17. The zone No. Z_(N) from each reading zone ofthe disc 1 is discriminated in the zone discriminating section 17. Thezone combination No. Z_(C) which is generated as a discrimination resultfrom the zone discriminating section 17 is supplied to the switchingdata ROM 18. The data dividing line data X (refer to 226 in FIG. 10)corresponding to the zone combination No. Z_(C) is supplied from theswitching data ROM 18 to the comparing section 19.

The comparing section 19 compares the data dividing line X from theswitching data ROM 18 and the count value A from the counter 21, therebycontrolling the switching operation of the switch 22. Namely, when thecount value A is equal to or larger than the data dividing line data X(region on the right side from the dividing line 226 in FIG. 10), theswitch 22 is switched to the OUT side, thereby allowing the data to beread out from the outside FIFO 12₀ and to be written into the errorcorrection memory 30. When the count value A is smaller than the datadividing line data X (region on the left side than the dividing line 226in FIG. 10), the switch 22 is switched to the IN side, thereby allowingthe data to be read out from the inside FIFO 12_(I) and to be writteninto the error correction memory 30.

The operation upon reproducing will now be described with reference toan operation flowchart of the reproducing apparatus of FIG. 14. Theoperation is accomplished by a control operation by the CPU 23.

In step S1, the pickups 16_(I) and 16₀ read the signals including thezone No. Z_(N) from the optical disc 1. The zone discriminating section17 discriminates the zone and checks to see if the combination iscorrect or not in step S2. If NO, the optical pickups 16_(I) or 16₀ ismoved to the next zone in step S3 so as to obtain a correct combination.

If YES in step S2, the clock signals C_(I) and C₀ in the read signalsfrom the optical disc 1 are extracted by the clock extracting sections15_(I) and 15₀ in step S20. In step S21, the data D is read on the basisof the clock signals C_(I) and C₀ from the optical disc 1. In step S22,the data D is decoded (in the decoding sections 31_(I) and 31₀) on thebasis of the clock signals C_(I) and C₀. In step S23, the data D fromthe decoding sections 31_(I) and 31₀ is written into the inside FIFO12_(I) and outside FIFO 12₀ on the basis of the clock signals C_(I) andC₀ in step S23. In step S24, the data dividing line data X is read outfrom the switching data ROM 18. In step S25, the comparing section 19compares the data dividing line data X and the count value A from thecounter 21.

In step S25, when X<A (region on the left side than the dividing line226 in FIG. 10), the reading clock signal C_(R) is supplied from themaster clock generating section 20 to the inside FIFO 12_(I) through theswitch 22 in step S26. In step S27, the data D is read out from theinside FIFO 12_(I) on the basis of the reading clock signal C_(R) and iswritten into the error correction memory 30. After that, a process instep S28 is executed. When X≧A in step S25 (region on the right sidefrom the dividing line 226 in FIG. 10), the reading clock signal C_(R)is supplied from the master clock generating section 20 to the outsideFIFO 12₀ through the switch 22 in step S29. In step S30, the data D isread out from the outside FIFO 12₀ on the basis of the reading clocksignal C_(R) and written into the error correction memory 30. Afterthat, step S28 is executed.

In step S28, the error correction and error extraction are executed inthe error correction memory 30 for the data D. After completion of theexecution of step S28, step S1 is again executed and the aboveoperations are repeated.

In FIGS. 13 and 14, the data of the disc inside recording area A_(I) andthe data of the disc outside recording area A₀ are always simultaneouslyread out from the inside recording area A_(I) and outside recording areaA₀ of the disc 1 synchronously with the clock signals C_(I) and C₀ andare written into the inside FIFO 12_(I) and outside FIFO 12₀,respectively. By the switching operation of the switch 22, either one ofthe data of the disc inside recording area A_(I) of the inside FIFO12_(I) and the data of the disc outside recording area A₀ of the outsideFIFO 12₀ is written into the error correction memory 30.

In the recording apparatus and reproducing apparatus shown in FIGS. 11and 13, the portions shown by the same reference numerals are theportions which can be commonly used in case of integrally constructingthose apparatuses as a single recording and reproducing apparatus.

In the flowchart of FIG. 12, when the information signal to be recordeddoesn't exist, the recording operation is finished without returning tostep S1. Similarly, in the flowchart of FIG. 14, when the informationsignal to be reproduced doesn't exist, the reproducing operation isfinished without returning to step S1.

According to the invention as described above, as compared with theconventional optical recording medium, the recording density can beimproved and the higher predetermined data transfer rate can beobtained. For example, the recording density is increased by about 4/3times and the data transfer rate is raised to a predetermined value thatis larger by about 5/4 times.

What is claimed is:
 1. An optical recording medium comprising:aplurality of recording areas arranged in ring shapes on a recordingsurface, an information signal being recorded in each of said recordingareas along spiral tracks, wherein a vortex direction of the spiraltrack of an outside recording area among said plurality of recordingareas differs from a vortex direction of the spiral track of an insiderecording area.
 2. An optical recording medium according to claim 1,wherein the information signal is recorded from an inner rim side of thespiral track in said inside recording area and the information signal isrecorded from an outer rim side of the spiral track in said outsiderecording area.
 3. An optical recording medium according to claim 1,wherein the spiral track of the outside recording area is continuous insaid outside recording area.
 4. An optical recording medium according toclaim 1, wherein the spiral track of the inside recording area iscontinuous in said inside recording area.
 5. An optical recording mediumaccording to claim 3, wherein the spiral track of the inside recordingarea is continuous in said inside recording area.
 6. An opticalrecording medium according to claim 1, wherein concentric zones aredefined in the plurality of recording areas and a recording density ofsaid information signal increases as a zone position moves from aradially innermost to a radially outermost concentric zone.
 7. Anoptical recording medium according to claim 6, wherein said recordingdensity differs in each of said concentric zones.
 8. An opticalrecording medium according to claim 7, wherein a sum of data transferrates of any zone in said outside recording area and a correspondingzone in said inside recording area is the same as the sum of datatransfer rates of any other zone in said outside recording area and itscorresponding zone in said inside recording area.